Climate Induced Thermocline Aging and Ventilation in the Eastern Atlantic Over the Last 32,000 Years
Abstract The radiocarbon analysis of uranium‐thorium‐dated cold‐water corals (CWCs) provides an excellent opportunity for qualitative reconstruction of past ocean circulation and water mass aging. While mid‐depth water mass aging has been studied in the Atlantic Ocean, the evolution of the thermocli...
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ftsubggeo:oai:e-docs.geo-leo.de:11858/11660 2024-04-28T08:30:31+00:00 Climate Induced Thermocline Aging and Ventilation in the Eastern Atlantic Over the Last 32,000 Years Beisel, Elvira Frank, Norbert Robinson, Laura F. Lausecker, Marleen Friedrich, Ronny Therre, Steffen Schröder‐Ritzrau, Andrea Butzin, Martin 2023-08-10 https://doi.org/10.1029/2023PA004662 http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/11660 eng eng doi:10.1029/2023PA004662 http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/11660 This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made. 14C dating 230Th/U dating Alboran Sea Angola Atlantic Azores Front Batm age cold-water coral Mauritania ventilation radiocarbon dating U/Th doc-type:article 2023 ftsubggeo https://doi.org/10.1029/2023PA004662 2024-04-03T14:31:33Z Abstract The radiocarbon analysis of uranium‐thorium‐dated cold‐water corals (CWCs) provides an excellent opportunity for qualitative reconstruction of past ocean circulation and water mass aging. While mid‐depth water mass aging has been studied in the Atlantic Ocean, the evolution of the thermocline is still largely unknown. Here we present a combined 14 C and 230 Th/U age record obtained from thermocline dwelling CWCs at various sites in the eastern Atlantic Ocean, with intermittently centennial resolution over the last 32 ka. Shallow dwelling CWCs off Angola, located in the South Atlantic, infer a link between the mid‐depth equatorial Atlantic and Southern Ocean. They confirm a 14 C drawdown during the Last Glacial Maximum (LGM) and advocate for a consistent Southern Hemisphere radiocarbon aging of upper thermocline waters, as well as strong depth gradients and high variability. Direct comparison with 14 C simulations carried out with an Ocean General Circulation Model yield good agreement for Angola. In contrast, the North Atlantic thermocline shows well‐ventilated water with strong variations near the position of today's Azores Front (AF), neither of which are captured by the model. During the Bølling‐Allerød, we confirm the important role of the AF in separating North and South Atlantic thermocline waters and provide further evidence of a 500 year long deep convection interruption within the Younger Dryas (YD). We conclude that the North and South Atlantic thermocline waters were separately acting carbon reservoirs during the LGM and subsequent deglaciation until the modern circulation was established during the YD. Key Points: North Atlantic cold‐water corals trace well‐ventilated thermocline waters near major oceanic fronts since the Last Glacial Maximum Across the South Atlantic into the Southern Ocean, aged waters with large variability and connectivity are evident during the last glacial The modern state of radiocarbon ventilation of the thermocline Atlantic is initiated during the Younger Dryas ... Article in Journal/Newspaper North Atlantic Southern Ocean GEO-LEOe-docs (FID GEO) Paleoceanography and Paleoclimatology 38 8 |
institution |
Open Polar |
collection |
GEO-LEOe-docs (FID GEO) |
op_collection_id |
ftsubggeo |
language |
English |
topic |
14C dating 230Th/U dating Alboran Sea Angola Atlantic Azores Front Batm age cold-water coral Mauritania ventilation radiocarbon dating U/Th |
spellingShingle |
14C dating 230Th/U dating Alboran Sea Angola Atlantic Azores Front Batm age cold-water coral Mauritania ventilation radiocarbon dating U/Th Beisel, Elvira Frank, Norbert Robinson, Laura F. Lausecker, Marleen Friedrich, Ronny Therre, Steffen Schröder‐Ritzrau, Andrea Butzin, Martin Climate Induced Thermocline Aging and Ventilation in the Eastern Atlantic Over the Last 32,000 Years |
topic_facet |
14C dating 230Th/U dating Alboran Sea Angola Atlantic Azores Front Batm age cold-water coral Mauritania ventilation radiocarbon dating U/Th |
description |
Abstract The radiocarbon analysis of uranium‐thorium‐dated cold‐water corals (CWCs) provides an excellent opportunity for qualitative reconstruction of past ocean circulation and water mass aging. While mid‐depth water mass aging has been studied in the Atlantic Ocean, the evolution of the thermocline is still largely unknown. Here we present a combined 14 C and 230 Th/U age record obtained from thermocline dwelling CWCs at various sites in the eastern Atlantic Ocean, with intermittently centennial resolution over the last 32 ka. Shallow dwelling CWCs off Angola, located in the South Atlantic, infer a link between the mid‐depth equatorial Atlantic and Southern Ocean. They confirm a 14 C drawdown during the Last Glacial Maximum (LGM) and advocate for a consistent Southern Hemisphere radiocarbon aging of upper thermocline waters, as well as strong depth gradients and high variability. Direct comparison with 14 C simulations carried out with an Ocean General Circulation Model yield good agreement for Angola. In contrast, the North Atlantic thermocline shows well‐ventilated water with strong variations near the position of today's Azores Front (AF), neither of which are captured by the model. During the Bølling‐Allerød, we confirm the important role of the AF in separating North and South Atlantic thermocline waters and provide further evidence of a 500 year long deep convection interruption within the Younger Dryas (YD). We conclude that the North and South Atlantic thermocline waters were separately acting carbon reservoirs during the LGM and subsequent deglaciation until the modern circulation was established during the YD. Key Points: North Atlantic cold‐water corals trace well‐ventilated thermocline waters near major oceanic fronts since the Last Glacial Maximum Across the South Atlantic into the Southern Ocean, aged waters with large variability and connectivity are evident during the last glacial The modern state of radiocarbon ventilation of the thermocline Atlantic is initiated during the Younger Dryas ... |
format |
Article in Journal/Newspaper |
author |
Beisel, Elvira Frank, Norbert Robinson, Laura F. Lausecker, Marleen Friedrich, Ronny Therre, Steffen Schröder‐Ritzrau, Andrea Butzin, Martin |
author_facet |
Beisel, Elvira Frank, Norbert Robinson, Laura F. Lausecker, Marleen Friedrich, Ronny Therre, Steffen Schröder‐Ritzrau, Andrea Butzin, Martin |
author_sort |
Beisel, Elvira |
title |
Climate Induced Thermocline Aging and Ventilation in the Eastern Atlantic Over the Last 32,000 Years |
title_short |
Climate Induced Thermocline Aging and Ventilation in the Eastern Atlantic Over the Last 32,000 Years |
title_full |
Climate Induced Thermocline Aging and Ventilation in the Eastern Atlantic Over the Last 32,000 Years |
title_fullStr |
Climate Induced Thermocline Aging and Ventilation in the Eastern Atlantic Over the Last 32,000 Years |
title_full_unstemmed |
Climate Induced Thermocline Aging and Ventilation in the Eastern Atlantic Over the Last 32,000 Years |
title_sort |
climate induced thermocline aging and ventilation in the eastern atlantic over the last 32,000 years |
publishDate |
2023 |
url |
https://doi.org/10.1029/2023PA004662 http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/11660 |
genre |
North Atlantic Southern Ocean |
genre_facet |
North Atlantic Southern Ocean |
op_relation |
doi:10.1029/2023PA004662 http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/11660 |
op_rights |
This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made. |
op_doi |
https://doi.org/10.1029/2023PA004662 |
container_title |
Paleoceanography and Paleoclimatology |
container_volume |
38 |
container_issue |
8 |
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1797588371125567488 |